With the exception of people in the 23- to 40-year-old age group (Gen Y or Millennials), American drivers are becoming increasingly skeptical of self-driving technology, according to a new study from research firm J.D. Power. And the widespread doubtfulness and apprehension represent a marketing hurdle for manufacturers and technology developers.

“In most cases, as technology concepts get closer to becoming reality, consumer curiosity and acceptance increase,” said Kristin Kolodge, executive director of driver interaction and human-machine interface research at J.D. Power. “With autonomous vehicles, we see a pattern where trust drives interest in the technology and right now, the level of trust is declining.”

Compared with the 2016 survey, 11% more Gen Z consumers (ages 13-22) and 9% more Pre-Boomers (age 72 and older) said they “definitely would not” trust automated technology.

However, similar to the 2016 study, consumers this year show great interest in collision protection and driving assistance technology. Six of the top 10 features that consumers were most interested in before learning the price — smart headlights, camera rear-view mirror, emergency braking and steering system, lane change assist, camera side-view mirrors and advanced windshield display — come from these two categories.

“Along with collision mitigation, there are many benefits to autonomous vehicles, including allowing those who are unable to drive in today’s vehicles to experience freedom of mobility,” Kolodge said. “Interestingly, though, 40% of Boomers do not see any benefits to self-driving vehicles. Automated driving is a new and complex concept for many consumers; they’ll have to experience it firsthand to fully understand it.”

Kolodge predicted, however, that as features such as adaptive cruise control, automatic braking and blind-spot warning systems become mainstream, drivers will gain more confidence in taking their hands off the steering wheel and allowing the vehicle to assume control.

The U.S. Tech Choice Study, now in its third year, examines consumer awareness, interest and price elasticity of various technologies by vehicle make and consumer demographic. This year’s study, conducted in January and February, was based on an online survey of more than 8,500 consumers who had purchased or leased a new vehicle in the past five years.